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11" Lens

Started by 1953, 04/02/2009 12:16PM
Posted 04/02/2009 12:16PM Opening Post
Well, here's a picture of the 11" objective I made for my scope.

It's a doublet with a slight air gap between the elements. The front element is made from O'hare's famous CPI1P (Cast Pig Iron One Pour), the rear element is Shot HD3/8PW (Home Depot 3/8" Ply Wood).

I can detect no spherical abberation of any kind, including spherochromatism. There are NO color crossings as there is no longitudinal color error from the deep dark red to radio frequency blue. Fifth order and all other abberations are zero. It's not sensitive to wedge and very tolerant of de-centering of the elements.

It was cheap to make (about 26 bucks) and NOT imported from China.

Jeff

Attached Image:

1953's attachment for post 46307

"Don't sweat the petty things and don't pet the sweaty things" 8O
Posted 04/02/2009 12:26PM #1
It seems that the central obstruction is rather large for an achromat. :S

dan
Posted 04/05/2009 06:30AM #2
First Light!!

Jeff

Attached Image:

1953's attachment for post 129469

"Don't sweat the petty things and don't pet the sweaty things" 8O